Oxygen is critical to life. When levels of oxygen change, it can have immediate and lasting impacts on a person's health.

Blood oxygen levels refer to the amount of oxygen circulating in the blood. Normal blood oxygen levels fall between 75 and 100 millimeters of mercury (mm Hg) on arterial blood gas (ABG) test results.

Lindsay Modglin is a nurse and professional writer who regularly writes about complex medical topics, as well as travel and the great outdoors. She holds a professional certificate in scientific ...

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